Serpentine tube heat exchanger assembly



Sept. 14, 1965 v. J. CARNS 3,205,940

SERPENTINE TUBE HEAT EXCHANGER ASSEMBLY Filed March 21, less s Sheets-Sheet 1 1 NTOR. VERNON J. RNS

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Sept. 14, 1965 v. J. CARNS 3,205,940

SERPENTINE TUBE HEAT EXCHANGER ASSEMBLY Filed March 21, 1963 3 Sheets-Sheet 3 52 .n:n. l

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VERNON J. CARNS fZww United States Patent 3,205,940 SERPENTINE TUBE HEAT EXCHANGER ASSEMBLY Vernon I. Cams, 3692 N. 15th Drive, Phoenix, Ariz. Filed Mar. 21, 1963, Ser. No. 266,923 5 Qiaims. (Cl. 165l44) This invention relates to a heat exchanger assembly and more particularly, to a heat exchanger assembly having a serpentine water heating passage structure therein, for use in continuous flow heating of water for various purposes.

Various water heating devices have been employed for continuous flow heating of water, and many of these devices have been found difficult to maintain because of a collection of mineral scale, internally thereof, due to low velocity flow through such prior art heat exchange devices. Additionally, many continuous flow heat exchange devices, having a serpentine flow passage therethrough, create a very high pressure drop from the inlet to the outlet thereof, due to ineflicient passage continuity internally of the heat exchanger.

Many of the prior art heat exchangers having serpentine flow pasages therethrough do not employ passage structure capable of maintaining a low pressure drop therethrough and minimum friction whereby, such prior art heat exchangers require excessively large and powerful pumps for forcing water through the passages of the heat exchanger.

From the foregoing, it will be clear that hard Water having a high concentration of minerals therein, may cause excessive scale accumulation internally of conventional hot water heater, heat exchange structures due to a low velocity of flow through such heat exchangers and a consequent lack of scrubbing velocity therethrough. Additionally, it will be appreciated that ineiflcient passage structure in the heat exchanger may cause a high pressure drop thereacross, greatly reducing the velocity therethrough, and also requiring unnecessarily powerful pumps for forcing the water through such heat exchangers.

Accordingly, it is an object of the present invention to provide a novel heat exchanger assembly having very efficient flow passage structure therein which provides for a minimum pressure drop from the inlet to the outlet of the heat exchanger with consequent high velocity therethrough applying a minimum amount of pump power, all of which contributes to the efficiency of operation of the heat exchanger, high velocity flow of fluid therethrough, and consequently low maintenance cost with high output performance.

Another object of the invention is to provide a very novel heat exchanger structure having a plurality of adjacent heat exchanger tubes having opposite open ends which are connected together by spaced headers and wherein recesses in the headers receive and hold projections of end plates in which very eflicient concave curved return bend passage structure provides eflicient transfer of liquid from one open end of one tube to an adjacent open end of the next tube through a turn of approximately 180 degrees. All of which, provides for a very simple and efficient heat exchanger of the continuous flow serpentine type.

Another object of the invention is to provide a very novel heat exchanger construction and means therein providing for simple removable installation of end plates having very eflicient return bend flow passage means which span adjacent open ends of substantially parallel heat exchanger tubes through approximately 180 degrees of the serpentine flow passage structures of the present invention Another object of the invention is to provide a novel header and end plate means, efllciently interconnecting a 3,255,949 Patented Sept. 14, 1965 plurality of parallel tubes in serpentine assembly, and wherein a novel inlet and outlet passage structure is incorporated in one of the headers to complete a serpentine passage structure of the invention.

Another object of the invention is to provide a heat exchanger structure adapted for heating water in a continuous flow serpentine passage structure having removable return bend passage means, which readily expose open ends of the heat exchanger tubes to permit descaling or maintenance without disconnecting inlet or outlet plumbing coupled thereto.

Another object of the invention is to provide, a novel heat exchanger assembly which serves as a continuous flow water heater, and which includes novel features of construction and assembly disposed to provide for overall efliciency of operation thereof, and which will require a minimum of maintenance and upkeep.

Further objects and advantages of the present invention may be apparent from. the following specification, appended claims, and accompanying drawings, in which:

FIGURE 1 is a fragmentary perspective view of one end of the heat exchanger, in accordance with the present invention, and showing portions broken away and in section to amplify the illustration;

FIGURE 2 is a reduced longitudinal sectional view of the heat exchanger of the invention taken from the line 2-2 of FIGURE 1;

FIGURE 3 is an enlarged fragmentary transverse sectional view taken from the line 33 of FIGURE 2;

FIGURE 4 is an enlarged transverse fragmentary sectional view taken from the line 4-4 of FIGURE 2; and

FIGURE 5 is a fragmentary plan sectional view taken from the lines 55, of FIGURES 3 and A The heat exchanger of the present invention comprises a plurality of hollow tubular Water passages composed of tubes 10, which are arranged in a substantially parallel assembly to each other, and which are provided with external heat exchange fins 12. The tubes 10 are provided with open ends 14, connected in sealed relation with a header 16. The tubes 10 are provided with opposite open ends 18, and these open ends 18, are coupled in sealed relation with a header 20.

The header 16 is provided with openings 22, through which the open ends of the tubes 10 communicate and in which the tubes 10 are fused or otherwise sealed, while the opposite ends 18, of the tubes 10, are fused or otherwise sealed in openings 24, through which open ends of the tubes 10 communicate.

The header 16 is provided with an inlet passage structure 26, having means for screwthreadably connecting plumbing therewith, and this header 16, is also provided with a hollow outlet 28, having internal screwthreads 3t disposed to receive screwthreaded plumbing fittings for the connection of water or of the fluid conduits thereto. It will be understood that the inlet 26 is also provided with internal screwthreads similar to the screwthreads 30, shown in the FIGURE 2 of the drawings, and that the header 16, together with the inlet and outlet passages 26 and 28, may be produced as a single casting.

This header 16 is provided with a recess which extends from the open ends of the tubes 14 and from the openings 22 to a face 32, shown best in FIGURE 2 of the drawings. The recess is provided with internal walls 34 and 36, between which a projection 38, of an end plate 40, is disposed. An inner end 42, of the projection 38, may be gasketed or otherwise sealed about the open ends 14, of the tubes 10, and a flange structure 44, of the end plate 40, is secured by bolts 46, to complemental flange structure on the header 16.

Disposed within the projection 38, are curved concave return bend recesses 48. These recesses 48 extend through approximately 180 degrees and span into communication with adjacent open ends 14 of the tubes 10, each recess 48 interconnects adjacent open ends 14, of two parallel tubes 10. As shown in FIGURE 3 of the drawings, some of these recesses are disposed with their longitudinal dimensions horizontally, While one of them is disposed in a diagonal direction, generally indicated at 50. These recesses 48, are cooperatively arranged relative to recesses 52, in an end plate 54, which is similar in construction to the end plate 40. However, the recesses 52, all extend in substantially vertical disposition, with respect to their longitudinal dimensions, so that Water entering the inlet 26, progresses into an inlet recess 56, then into one end of one of the tubes 10, and then into a recess 52, in the end plate 54, as shown in FIGURE 2 of the drawings, the recesses 52 being similar in construction to the recesses 48, hereinbefore described.

As the water progresses from the recess 52, shown in FIGURE 2 of the drawings, it comes back into a recess 48, designated 57, and is transferred to the next adjacent recess 52 via the tubes 10, whereby it is returned to the next horizontal recess 48, designated 58, whereupon it is transferred to another of the recesses 52 and again returned to a recess 48, hereinbefore designated 50, and shown in diagonal position in FIGURE 3 of the drawings. The water then passes to another of the recesses 52 and is returned to a recess 48 particularly designated 60, where upon it is transferred through another of the recesses 52 to an outlet recess 62 communicating with the outlet 28. Thus, the water by means of the return bend recesses 48 and 52 traverses the interiors of the tubes successively in a serpentine fashion so that water continuously flows through these tubes and whereby the curved return bend recesses 48 and 52 provide for eificient change of direction of the water for 180 degrees as it reaches, alternately, each of the end plates 40 and 54. Thus, the water may be forced at high velocity through the entire assembly of tubes 10 successively and in serpentine fashion without a high pressure drop due to the efliciency of the curved concave recess return bend structures 48 and 52, in the respective end plates 40 and 54.

It will be understood that the projecting structures of the end plates 40 and 54, which contain the recesses 48 or 52, respectively, are held in recesses in the headers 16 and N, and these headers are provided with recesses, generally formed by a box-shaped structure, having walls similar to the walls 34 and 36, hereinbefore described, and having end walls 35 and 37 integral therewith as shown in FIG- URE 4, to provide a box structure surrounding the recess in which the projection of each end plate is located. The flange structure 44, of the end plate 46, held by the bolts 46, may be gasketed to the outer surface 32 of the header 16, while a similar flange structure 64 integral with the end plate 54, may be held to the respective header 20 by means of bolts 66.

The end plate 54 is provided with an internally screwthreaded opening 68, which communicates with one of the arcuate return bend recesses 52, as shown best in FIGURES 2 and 4 of the drawings. This internally screwthreaded opening 68 provides facility for connecting plumbing to the end plate 54, in communication with the serpentine flow path internally of the heat exchanger of the present invention, at a meeting point therein.

As shown in FIGURE 1, the internally screwthreaded inlet and outlet passage portions 26 and 28, are disposed for the connection of inlet and outlet plumbing, communicating with the serpentine flow path through the heat exchanger. Internally screwthreaded plumbing fitting openings 27 and 29 communicate with the inlet and outlet passages 26 and 28 respectively, and are thus disposed for convenience in connecting complemental plumbing fittings therewith.

It will be appreciated by those skilled in the art, that the recessed headers 16 and 20 provide receptacles for the extending portions of the end plates 40 and 54, in

which the curved concave return bend flow passage recesses are disposed. Thus, the extensions of the end plates into the recessed headers, provides a novel combination for receiving, supporting, and structurally aligning, the return bend recess structures in the end plates, with opposite open ends of the tubes 10. Additionally, these recesses, hereinbefore described, namely those recesses 48 and 52, in the end plates 40 and 54, may readily be cast in smooth configuration to provide a minimum of turbulence or boundary layer friction as the fluid passes through the heat exchanger, and particularly, around the -degree reverse bends, communicating with and abridging adjacent open ends of the tubes 10.

As hereinbefore described, the walls 34, 35, and 36, and comparable structure of each of the headers 16 and 20, properly receives and aligns, and structurally supports the extended portions of the respective end plates 40 and 54 so that their return bend recesses properly align with and abridge adjacent open ends of adjacent heat exchange tubes 10, so that a serpentine flow passage through the heat exchanger may be attained from the inlet 26 to the outlet 28, as hereinbefore described.

It will be appreciated by those skilled in the art that the fins 12 extend the surface area of the tubes 10, and receive heat from any suitable source such as a gas burner or the like.

In service, the end plates 40 and 54 may readily be removed by loosening the respective bolts 46 and 66, and the interior of the tubes 10 may readily be cleaned by passing a suitable brush longitudinally therethrough.

Additionally it will be appreciated that this maintenance work may be accomplished without disconnecting inlet and outlet plumbing which is secured on one of the headers.

It will be appreciated by those skilled in the art, that various modifications of the present invention may be resorted to in a manner limited only by a just interpretation of the following claims.

I claim:

1. In a heat exchanger, the combination of: a pair of spaced headers; a plurality of heat exchange tubes having opposite open ends interconnecting said headers; each of said headers having a header recess which communicates with all of said open ends of said heat exchanger tubes; each of said recesses having an open side spaced from said open ends; a wall of each header disposed at an inner portion of each header recess, each wall having a plurality of openings extending therethrough; said opposite open ends of said tubes communieating through said openings in said walls, and end plates each having a projection extending into one of said recesses, each projection having a curved concave return bend communicating recess spanning a pair of adjacent open ends of said tubes and forming a continuity of passage structure extending through approximately a 180- degree turn from one open end of one heat exchange tube to another open end of an adjacent heat exchange tube.

2. In a heat exchanger, the combination of: a pair of spaced headers; a plurality of heat exchange tubes having opposite open ends interconnecting said headers; each of said headers having a header recess which communicates with all of said open ends of said heat exchanger tubes; each of said recesses having an open side spaced from said open ends; a Wall of each header disposed at an inner portion of each header recess, each wall having a plurality of openings extending therethrough; said opposite open ends of said tubes communicating through said openings in said walls, and end plates each having a projection extending into one of said recesses, each projection having a curved concave return bend communicating recess spanning a pair of adjacent open ends of said tubes and forming a continuity of passage structure extending through approximately a 180-degree turn from one open end of one heat exchange tube to another open end of an adjacent heat exchange tube inlet and outlet passages in one of said headers, communicating with said respective header recess therein and open ends of a pair of said tubes; and means removably securing said end plates to said headers whereby open ends of said heat exchange tubes may be exposed for cleaning the same and whereby one of said end plates may be removed from one of said headers without disturbing conduits and plumbing which is adapted to be used in connection with said inlet and outlet passages.

3. In a heat exchanger the combination of: a pair of spaced headers; a plurality of heat exchange tubes each having opposite open ends interconnecting said headers; each of said headers having a header recess which communicates with open ends of said tubes; each of said recesses having an open side spaced from said open ends of said tubes; a Wall of each header disposed at an inner portion of each header recess, each wall having a plurality of openings extending therethrough; said opposite open ends of said tubes communicating through said openings in said walls, and end plates each having a projection extending into one of said recesses, each projection having a plurality of concave return bend communicating recesses spanning pairs of adjacent open ends of said tubes and forming a continuity of passage structure extending through approximately a ISO-degree turn from each open end of each heat exchange tube to another open end of an adjacent heat exchange tube.

4. In a heat exchanger the combination of: a pair of spaced headers; a plurality of heat exchange tubes each having opposite open ends interconnecting said headers; each of said headers having a header recess which communicates with open ends of said tubes; each of said recesses having an open side spaced from said open ends of said tubes; a wall of each header disposed at an inner portion of each header recess, each wall having a plurality of openings extending therethrough; said opposite open ends of said tubes communicating through said openings in said walls, and end plates each having a projection extending into one of said recesses; each projection having a plurality of concave return bend communicating recesses spanning pairs of adjacent open ends of said tubes and forming a continuity of passage structure extending through approximately a ISO-degree turn from each open end of each heat exchange tube to an- 6 other open end of an adjacent heat exchange tube; said concave curved return bend communicating recesses disposed to connect opposite ends of said tubes in a manner to provide a serpentine passage for water to flow consecutively through said tubes and alternately toward and away from each of said respective headers.

5. In a heat exchanger the combination of: a pair of spaced headers; a plurality of heat exchange tubes each having opposite open ends interconnecting said headers; each of said headers having a header recess which communicates with open ends of said tubes; each of said recesses having an open side spaced from said open ends of said tubes; a wall of each header disposed at an inner portion of each header recess, each wall having a plurality of openings extending therethrough; said opposite open ends of said tubes communicating through said openings in said walls, and end plates each having a projection extending into one of said recesses, each projection having a plurality of concave return bend communicating recesses spanning pairs of adjacent open ends of said tubes and forming a continuity of passage structure extending through approximately a ISO-degree turn from each open end of each heat exchange tube to another open end of an adjacent heat exchange tube; said concave curved return bend communicating recesses disposed to connect opposite ends of said tubes in a manner to provide a serpentine passage for water to flow consecutively through said tubes and alternately toward and away from each of said respective headers; some of said concave curved return bend communicating recesses being angularly disposed relative to others of said concave return bend communicating recesses.

References Cited bythe Examiner UNITED STATES PATENTS 967,974 8/10 Purfurst 72 1,542,613 6/25 Cox 165158 2,183,956 12/39 Campbell et a1 165l58 X 2,363,118 11/44 Chamberlain 165-158 X ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner. 

1. IN A HEAT EXCHANGER, THE COMBINATION OF; A PAIR OF SPACED HEADERS; A PLURALITY OF HEAT EXCHANGE TUBES HAVING OPPOSITE OPEN ENDS INTERCONNECTING SAID HEADERS; EACH OF SAID HEADERS HAVING A HEADER RECESS WHICH COMMUNICATED WITH ALL OF SAID OPEN ENDS OF SAID HEAT EXCHANGE TUBES; EACH OF SAID RECESSES HAVING AN OPEN SIDE SPACED FROM SAID OPEN ENDS; A WALL OF EACH HEADER DISPOSED AT AN INNER PORTION OF EACH HEADER RECESS, EACH WALL HAVING A PLURALITY OF OPENINGS EXTENDING THERETHROUGH; SAID OPPOSITE OPEN ENDS OF SAID TUBES COMMUNICATING THROUGH SAID OPENING IN SAID WALLS, AND END PLATES EACH HAVING A PROJECTION EXTENDING INTO ONE OF SAID RE CESSES, EACH PROJECTION HAVING A CURVE CONCAVE RETURN BEND COMMUNICATING RECESS SPANNING A PAIR OF ADJACENT OPEN ENDS OF SAID TUBES AND FORMING A CONTINUITY OF PASSAGE STRUCTURE EXTENDING THROUGH APPROXIMATELY A 180DEGREE TURN FROM ON OPEN END OF ONE HEAT EXCHANGE TUBE TO ANOTHER OPEN END OF AN ADJACENT HEAT EXCHANGE TUBE. 